Question

sabendo que log2 7 = 3,1 , log2 3 =1,2 e log2 4=2, calcule

a)log2 (21)

b)log2 9

Answer 1

a)

$log_{_2}(21)~=\\\\\\=~log_{_2}(3~.~7)\\\\\\Utilizando~a~propriedade~do~logaritmo~do~produto\\\\\\=~log_{_2}3~+~log_{_2}7\\\\\\=~3,1~+~1,2\\\\\\=~\boxed{4,3}$

b)

$log_{_2}(9)~=\\\\\\=~log_{_2}(3^2)\\\\\\Utilizando~a~propriedade~do~logaritmo~do~expoente\\\\\\=~2~.~log_{_2}3\\\\\\=~2~.~1,2\\\\\\=~\boxed{2,4}$